1. Field of the Invention
The present invention relates to a die for forming a honeycomb structure, and a method of manufacturing the die. The present invention particularly relates to a die for forming a honeycomb structure, which realizes a high formability and which has an excellent resistance to wear, and a method of manufacturing the die.
2. Description of the Related Art
As a method of forming a honeycomb structure made of a ceramic, a method has heretofore been performed broadly in which a forming material (clay) is extruded using a die for forming the honeycomb structure. The die comprises a die base provided with back holes for introducing the material therethrough, and slits of a lattice shape which communicate with the back holes. As to this die, usually in one surface of the die base, slits having widths corresponding to partition wall thicknesses of the honeycomb structure are arranged in the lattice shape or the like, and in an opposite surface (the other surface), the back holes communicating with the slits are opened in large areas. Moreover, the back holes are usually arranged in positions where the slits of the lattice shape or the like intersect each other, and the back holes communicate with the slits inside the die base. Therefore, a forming material, such as a ceramic material, introduced from the back holes, shift from the back holes having comparatively large inner diameters to the narrower slits, and is extruded as a formed article having a honeycomb structure from an opening of each slit.
Examples for use as the die base constituting the die for forming the honeycomb structure include: a plate-like member (die precursor) made of one type of alloy such as a stainless alloy or a super hard alloy; and a plate-like member (die precursor) obtained by bonding two different types of plate-like members together (e.g., Japanese Patent Application Laid-Open No. 2000-326318 and Japanese Patent Application Laid-Open No. 2003-285308).
However, as to the die base using a stainless steel or the like, since a resistance to wear of the substrate is low, there has been a problem that slits are worn by continuous extrusion, and a shape of an extruded honeycomb article gradually changes. Since the die base using the super hard alloy is superior in resistance to wear, the wear on the slits can be reduced. Conversely, when the back holes little influenced by the wear or the like are disposed, there is a problem that much labor and time are required. Since the super hard alloy is a brittle material, there is a problem that the die is broken by a pressure at an extruding time.
Moreover, for example, the die base (die precursor) is used in which two different types of plate-like members are bonded to each other. In this case, even if the slit is disposed which corresponds to the width of the partition wall of the honeycomb structure to be extruded, there has been a problem that the width of the slit is deformed after machining, and the honeycomb structure having a predetermined shape cannot be extruded because of the presence of a large residual stress. There has also been a problem that the super hard alloy is easily cracked, and a working tool such as an abrasive wheel is easily broken during the machining of the die base (die precursor).